Compressor



May 4 192 J. DUBROVTN COMPRESSOR I Filed April 28. 1924 i 1 M a if u 9 54 umm Patented May 4, 1926.

UNITED STATES.

A ENT OFFICE."-

. JOHN nUEnOvIIv, OE CHICAGO, ILLINOIS, SSIGNOE, BY MESNE ASsIGnMEn'rs, r0

UNIVERSE CORP R TION, OE CHICAGO, ILLINOIS, A CORPORATION OE ILLINOIS.

COMPRESSOR.

Application filed April 28, 1924. Serial No. 709,472.-

My invention relates to air or gas com-- pressors of the general type employing a re.

ciprocating piston, and 1n some of its general aspects aims to provide simple and effective means for eliminating the noise commonly caused by the seating of the movable cylinder head, for effectively reducing the clearance between the piston and the cylinder head so as to increase the degree of compression and the efliciency of the compressor, and for separating the compresseed air or other gas from lubricating oil.

In U. S. Patent No. 14150122 of March 27, 1923, there is disclosed a compressor of this general class employing a lifting head for the cylinder and provided with an oil separating chamber in which the lubricating oil which has passed beyond the cylinder into the compressing chamber is separated from the compressed gas. While this arrangement has afforded asatisfactory separation of the oil from the gas and an automatic return of the separated oil to the crank chamber. of the compressor itjinvolves a bulky and relatively expensive construction, since 1t requires the providing of an additional oil sep aratin-g chamber and' of suitable baffle ar'- ran'gements within the latter. My present invention provides a simple but effective substitute for this auxiliar providing separate out ets from the discharge chamberfor the compressed gas and the oil respectively, by arranging these Outlets so that the compressed airflowing fromthis chamber will be practically free of oil instead of carrying oil with it, and by shaping the discharge chamber sothat o'il creeping up its inner wall Will be forced away from this wall.

oil separator by The said patent also disclosed the use of alight and bodily movable cylinder head normally held in its closure position by a spring, together with, simple means for retaming a suh'icient quantity of lubricating Oil within the compression chamber above this head to aid both in 'afiording a tight seal for the outlet end of the cylinder and in reducing the noise-due 'to'theseating of the head. \Vhile this feature also has given advantageous results, compressors constructed Withthe same have notbeen as free from noise as is desirable for certain purposes, as for example when such a compressor is employed as part of a mechanical refrigerating unit designed for household use. Furthermore, since the width of the flat seat portion required for such a-cylinder head introduces a considerablefriction or wire-drawing ef-.

fect, this has retardedthe securing of the desired high compression with a relatively slow rate of operation of the compressor.

My present invention aims to overcome the objections on the score of noise by providlng a seat and head arrangement in which the headfengages the end of the ."cylinder only along a single circular line atthe moment Of its seating or unseating, thereby affording so small a contact surface that the intervening slight film of oil can adequately cushion the same, and thereby also eliminating, the noise-producing sudden ex ul sion'of a considerableamount of'air an oil 'a cylinder head by providing adlvergence between the movable cylinder head and the adjacent end of the cylinder and by arranging the head so that its separation from the cylinder will be only along a single line in stead of along an annular surface of'consid erable area.

Furthermore, my lnvention provides a movable cylinder head arranged so.th-at it will be flexed into the adjacent end of the cylfrom between the head and the seat. It also I inder to some extent when in its closure po- .sition and provides a piston having a correspondingly recessed rear end adapted to cooperate with the flexing of the cylinder head for permitting the operation of the compressor with an exceedingly small clearance between the piston and the head, thereby 1ncreasing the effective rate of compression and greatly expediting thejattaining of a thereby desired ,degree'of compression.

My invention also provides such an inte terior shape for the chamber into which the compressed gas is discharged that oil which has entered this chamber will be projected away from the inner wall of this chamber,- reventing the movement of thegasfrom ai ing capillary action in moving the oil ,further toward the dischargeoutlet of the" chamber.

Still further-and also more detailed objects will appear frointlie following specification and from the accompanying-drawings,'in Whlbhrw 1 Fig. 1 is a central and vertical section through a compressor embodying my inven-.

'. tion, showing the piston at the lowest point o-f its travel.

Fig. 2 is an enlargement ofa portion of Fig. 1 with the piston in a more elevated position and the cylinder head in the effective closure position which it accompanies 80 during the major part of the'reciprocatory movement of the iston.

i Fig. 3 is a section similar to Fig. 2 but showing. the piston substantially at its high- 1 est point, and also showing the movable cyl'-" inder head the-position occupied by it "just before it is raised off thevadjacent" end of the cylinder orwhen it has just'returned to this seat-forming end by the spring. i

Fig. 4; is a section similarto Fig. 3, but showing the use of a movable head which is normally convexed downwardly tov a less extent than the slope of the annular seat.

Fig. 5-is a view'ot a desirable. form of spring for use-with my invention.

Referring to the embodiment oftlie draw-- ings, FigI-l shows a compressor having a vertical cylinder 1 supportedby a crank on sing 2 and surmounted by a discharge chamber 3 having its'lower end of large'r'interior' diameter than the bore of the cylinder.

Owing to this divergence in diameters, the

cylinder presentsan annular end portion 4 directed" upwardly into. the pressure cham-' her 3 and-adapted to afiord a seat for the,

eflective seal.- During the downward or' ntake movement of thepiston, the result f g 4 during a portion of the upward or pressing stroke of the piston.-

This gas outlet duct 7 desirably extends through a side wall ofthe' pressure chamber 3'for aconsiderable dlstance into thesa d chamber, .as shown for example in Fig. 1.'-

I also provide an oil' outlet tubes which tube desirably extends vertically downward through thetop of the chamber 3 .to a point somewhat higher than the extreme'height to which the head 5 will be lifted in practice against the resistance of the spring 6. This springdesirably tapers upward so that .its upper end is sleeved upon the tube -8 for holding the spring axiall central ofgthe cylinder and-its upperend desirably-abuts against a suitablethrtist member, such as a collar 9secured to the oiloutlet tube 8,while the lower end. of the spring desirably has a substantially complete annular bearing, Surface of a diameter .closely. approximating the'bore of the cylinder. Slidable within the cylinder 1 is apiston 10 connected by the usual pitman 11. to the pin 12 of the actuating crank ofi-the' compressor, the cylinder having a suitab'lydisposed gas inlet 17. I In constructing a compressorafter the manner above described, I desirably employ a spring 6 of sufficient strength for normally convexingthe head 5 downwardly after the manner shown in Fig. 2, so that the radially outward portion of 'theliead will correspond substantially in shape to the slope of the annular seat 4:, thereby afiording a wide seating engagement and a consequently highgly suction will cooperate with the pressure of the spring inholding the head in tight s'eaL ing engagement with the seat and thisfseati ing of a wide radially outer portion of the head on the annular seat 4- continues l I Then, as the pressure ofI the' flu'idi en-l trapped in the cylinder betweenthepiston' and the movable head 5 increases-this pres sure ,will gradually overcome theresistanceof the 'spring 6 with. the initia1 m ul t f permitting the resili y g metal return the head to its te ms flat shepev while the spring st1lL're's'i sfg-a bodilylifting of the head and'k'ee-ps the of the lower face of the head in engagement with the seat as shown in Fig. In other". words-,- the downward convexing of thehead gradually decreases during the upwardstroke of the piston so as tq reduce .thejextent-of: the seating. engagement until this engagement between the head and $1.19 t i merely 130 along a single circular line. After this mer'elinear engagement of the head with the seat has been reached, the continually increasing pressure below the head reaches a point -where it overcomes the resistance of the spring and lifts the head bodily off its seat in the usual manner so as to allow the compressed fluid. t6 escape betweenthe' edge of the head and the bore of the chamber In thus issuing from the cylinder, the compressed gas has a relatively wide opening provided for it at the mouth of the cylinder and this opening is at its narrowest; only along'the very edge of themovable head, so

that the gas is not discharged through a relatively wide passage of quite-restricted height as would be the case if the portion of the head opposite the seat was continuously of a cross-section corresponding'to that of' the seat. Consequently, I practically; avoid the socalled-Fwire drawing or pressure reducing effect encountered with the older constructions of compressors employing bodily movable .cylinderhe'ads, and hence can attain both a higher compression in the discharge chamber 3 and a more rapid dis charge of the compressed fluid into the said chamber. I

To increase the obtainable pressure still further, I" desirably concave the upper end (or the end facing the movable.

of the piston head 5) as shown in Figs. '2 and 3, so as to correspond. in central transverse section to that of the movable head when the latter is flexed into its downwardly convexed and -firmly seating shape. By so doing, 1 can cylinder,

provide an unusually close approach of the piston to the end of the bore of the cylinder without the risk of having the piston come into contact head. a v

To securethe-needed continuous lubrication of the piston, crank and pitman, I; desirably provide a suflicient'quantity of lubricating oil' in the crank casing 2 so that the crank will continuously splash some of this upward'into the bore of'the cylinder. Since at any time with. the 'movable some of this oil will also be carried up by -the piston to the upper portion of the. oil will be carried into the cham eachcharge of the compressed gas her 3 with and will gradually form a layer of oil in the bottom of the said chamber. As soon as this layer extends above the bottom of the oil tube 8, the pressure of the gas which'is' gradually discharged from the chamber 3 through the relatively small bore of the outlet tube 7 forces the oil out through the oil duct 8. This duct is desirably connected through a differential 'valve 14 to an oil 'return tube leading to-the interior of the crank casing, the said valve; being arranged after themanner of the said Patent No. 1,4:J22 for permitting oil to pass from the duct 8 to the oil return tube Mwhenpressed gas can only assist ever the pressure within the crank casing falls to a predetermined point.

'By' arrangingthe gas outlet pipe 7 so thatits'inlet is disposed at a considerable.

height above the'head 5, I preventthis from being reached by the fine spray in which the oil is carried into the chamber 3 :with

the compressed gas entering this chamber. However, this finely sprayed oil might be carried upward along the inner' wall of the chamber 3 by capillary action and might be drawn into the tube 7 if the latter had .its inlet flush with the said inner wall, hence my desirably extending the gas discharge tube? for a considerable distance beyond the wall of the chamber ,3 intov the latter, as shown for example inFig. 1. Ialso desirably provide the discharge chamber only for a re atively short height above the said annular seat with a bore approaching the diameter of the movable cylinder head and then widen this chamber considerably as shown in Figs. 1 and 2,-.and preferably provide a sharp shoulder at the juncture between these'two. portions of the chamber.

\Vith the bore otqthe discharge chamber thusflformed, the movement of the comin carrying the oil along the contracted bore portion up to this shoulder, after which the succeeding upward rushesof gas will project; the oil substantially vertically or away capillary action from the widened lateral wall portion of the chamber as shown by; the arrow A of Fig. 2. Almost all of the oil thus removed from the wall of the chamber is collected by gravity oi 'erthemovable cylinder head and later-is .forced out through the oil tube 8,

so that this shaping of the discharge chamber cooperateswith the disposition of the gas outlet tube 7 in affording an effective separation of the oil from the gas. By so doing, I'have found that I can effectively separate the lubricating oil from the compressed gas within this chamber without requiri'ngan auxiliary separating chamber or oil separating baffles alter the manner shown in U. S. Patent No. 1,450,122.

' However, while I have heretofore illustrated and described my *invention in a i highly desirable embodiment l do not wish .to be limited to the various details of conlifting of the head and for maintaining the edge of the head in engagement with the the spring employed for resisting the bodily seat until the head has returned to normal shape might be of a diameter diifermg considerably from that of the cylinder bore.

engaging-turn forming an almost complete circle and ground to. afford a bearing in a plane at right angles to the axis of the spring. I also desirably make the boreof the chambcrfi only slightly larger diameter than the head, so that this borewill 'aflord a,guide for limiting the lateral movediameter than the outer diameter of the seat,

ment of the hcad in any directon.

'Vtfith such a compressor of such a con- 2 struction in' operation, it will be obvious that after the head has been lifted ofl' its seat, the return seating movement will 'initially cause the head to engage the seat only surfaces after the manner of flatwise seat-f along the single line of its circular edge, so

that I do not obtain the loud slapping noise.-

which is produced whenever a pair of relatively wide surfaces are suddenly brought into contact-with each other. Furthermore,

since there initially is a gap of considerable heightzbetween the head and the extreme ing contacts, and the subsequent gradual convexing of the head affords no noise whatever. Consequently, I have found that my exceedingly s mple arrangement eife ctively overcomes-the noise which has heretofore. been considered unavoidable with compressors having bodily movable cylinder heads. Moreover, the film of oil upon the seat. cooperates with the tightening of the 'seal,- so that I can secure a highly effective closure', even through the seat does not conform exactly in its slope to the curvature of the adjacent head portion. Owing to this effective sealing, together with the elimination of the usual wire drawing and the reduction in the clearance between the piston and the head; I am able to secure a decided increase in the compression obtained with a piston of given diameter and stroke in a given number ofreciprocations', so that with a given size of compressor and a given rate;

of reciprocation I can attaina desiredi degree of compression much more quickly than I could without employing the above disclosed novel features. Furthermore, I do not wish to I ployedseparately.

1. In-a compressor, a cylinderhaving atits discharge end an outwardly concaved I 'claim as my invention annular' seat; an imperforate circular and normally fiat head of smaller diameter thanthe outer diameter of the seat and of a resilient and normally flat material adapted to be convexed toward the cylinder to a spherical curvature conforming substantially to the concaving of theseat; and a spring having an annular end portion 'of smaller diameter than the head and disposed "with this end engaging'the head on the side-opposite the cylinder and cooperating with suction in the cylinder. to flex the head to the said seatfitting spherical curvature. I

2. In a compressor, a cylinder having at its discharge end an outwardly concaved annular seat, an imperforate head of smaller the head being of a resilient and normally flat material adapted to be convexed toward 'the cylinder to a spherical curvatureclosely fitting the concaving of the seat while continuously maintaining the outer edge of the head in engagement with the seat, and

a;compr'ession'spr1'ng axially concentric with the cylinder and urging the head toward the cylinder, the spring having a head-engaging annul'ai" portion of a diameter not greater than the bore' of the cylinder.

'3. In a compressor,a, cylinder having at its discharge end an'annular. seat flaring outwardly of thecylinder; an imperforate, cir-.' cular and resilient head having 'a diameter greater than the bore of the seat and having ts resiliency tending to maintain the head in'a shape 'inwhich it engagesthe seat only along the edge of the face directed toward the seat, and spring means continuously urging the head toward the seat and adapted to flex the head into a shape in which it en gages an annular seat portion of considerable width. v

4:. In acompressor, a cylinder having at its discharge end an annular seat, a nor" mally flat head of thin resilient material having a diameter greater than the bore of the seat and engaged only along its edge by the seat when the head is flat, the head beingadapted to be convexed toward the cylinder so as tohave it bear against an annular seat portion of considerable width,;

and spring means continually urging the. p

head toward theseat and engaging the head at a plurality of points spaced radially inward by a considerable distance from the edge of thefihea'd, whereby the spring'will cooperate with the bearing of the edge. of the head against'the seat to convex the head into its said :wider seat-engaging disposibe limited 0 to the conjoint use of these various novel features, as they might obviously be eln-f tion.

q 5. The combination with the {cylinder of a compressor, ofa compressed gas chamber into which discharge end of the cylinder ing the head towards the cylinder, an oil" discharge pipe extendin into the chamber to a point near thehea and a compressedgas discharge pipe connected to the 'said! chamber and having its inlet spaced by a considerable distance fromthe said head.

.- 6. A compressor as per claim 5, iniwhich the cylinder and the compressed gas chamber are in vertical alinement with the chamher above the cylinder, and in which the gas discharge pipe extends into the chamber and has. itsinlet spaced by a considerable distance from the inner Walls ofthe, chamber.

Signed at Chicago, Illinois, Apri1'22nd,

' JOHN DUBROVIN. 

